High density printed circuit board and edge connector assembly

Abstract

A high density printed circuit board carrying integrated circuits or the like is provided with two parallel rows of terminals along one edge on both sides of the board. The terminals in the outer row of terminals closest to the edge of the board are connected to printed circuits on inner layers of the multiple layer printed circuit board by plated-through holes or other suitable techniques; and the printed circuits on the outer layer or layers are connected to the inner row of terminals spaced just inside the outer row of terminals. A circuit board connector is provided with spring contacts which are electrically insulated from one another but which are designed to engage the multiple layer printed circuit board at the position of the first and second rows of terminals. The spring contacts engaging the inner row of terminals on the circuit board are longer in length than those engaging the outer row of terminals, and are thus easily deflected so that the P.C. board may be inserted or removed from the connector without excessive force.

What is claimed is: 
     
       1. A high density printed circuit board and edge connector assembly comprising: a high density printed circuit board having a printed circuit pattern on said board and a printed circuit pattern within said board;   a first row of terminals located on said board adjacent one edge of said printed circuit board;   a second row of terminals located on said board coplanar with said first row of terminals and spaced back from said edge further than said first row of terminals;   connections to said first and second rows of terminals consisting of conductor means extending from said printed circuit pattern within said board to terminals in said first row and extending from said printed circuit pattern on said board to terminals in said second row; and   an edge type circuit board connector including a housing for receiving and positioning said board, and first and second sets of spring type electrical contact means located to engage said first and second rows of terminals respectively.   
     
     
       2. A high density connector as defined in claim 1 wherein said first spring contact means are substantially shorter than said second spring contact means. 
     
     
       3. A high density connector as defined in claim 1 wherein each of said contact means includes a curved conductor strip and means are provided for mounting each said conductor strip to engage a different circuit board terminal along a tangent to said curved strip. 
     
     
       4. A high density assembly as defined in claim 1 wherein said printed circuit board is a multilayer printed circuit board and wherein plural printed circuit patterns, including said printed circuit pattern within said board, are located on inner layers of said board. 
     
     
       5. A high density assembly as defined in claim 4 wherein said conductor means includes plated-through holes interconnecting selected printed circuit patterns on inner layers of said multilayer printed circuit board with selected terminals included in said first row of terminals. 
     
     
       6. A high density assembly as defined in claim 5 wherein said plated-through holes are connected to said first row of terminals, to minimize cross-over connections. 
     
     
       7. A high density assembly as defined in claim 5 wherein said plated-through holes extend substantially all of the way through said printed circuit board. 
     
     
       8. A high density assembly as defined in claim 7 wherein first and second sets of said plated-through holes are provided at respectively different distances from said edge of said board, two rows of terminals are located on both sides of said printed circuit board along one edge thereof, and wherein the row of terminals adjacent the edge of said board on one side are located a predetermined distance from said edge and are in electrical contact with said first set and are isolated from said second set of plated-through holes, and wherein the row of terminals adjacent the edge of said board on the other side of said board is located at a different distance from the edge of said board and are in electrical contact with said second set and are isolated from said first set of plated-through holes. 
     
     
       9. A high density assembly as defined in claim 5 wherein said plated-through holes only extend to one of the side surfaces of said printed circuit board. 
     
     
       10. A high density assembly as defined in claim 5 wherein said two rows of terminals and said conductive printed circuit pattern on said board all lie in substantially the same plane. 
     
     
       11. A multilayer printed circuit board and edge connector assembly comprising: a multilayer printed circuit board having inner and outer layers and printed circuit patterns associated with said layers;   first and second parallel rows of terminals located on one outer layer and adjacent one edge of said board and coplanar with the printed circuit pattern associated with said one outer layer, said second row spaced back from said edge further than said first row and connected to the printed circuit pattern associated with said one outer layer;   connections to said first row of terminals consisting of conductive plated-through holes extending from the inner layers of said board and interconnecting the printed circuit patterns associated with said inner layers to terminals in said first row;   an edge type circuit board connector, including a housing for receiving and positioning said board, a first set of elongated resilient contacts deflectable by the insertion of said board for engagement with said first row of terminals, and a second set of elongated resilient contacts overlying and insulated from said first set of contacts and also deflectable by the insertion of said board for engagement with said second row of terminals, said second set of contacts being substantially longer and requiring less initial force for deflection than said first set of contacts whereby the insertion and removal force for said board is not excessive.